Python: Find the first negative balance

Python Programming Puzzles: Exercise-70 with Solution

Write a Python program to find the first negative balance from a given a list of numbers which represent bank deposits and withdrawals.

Input:
[[12, -7, 3, -89, 14, 88, -78], [-1, 2, 7]]

Output:
[-81, -1]
Input:
[[1200, 100, -900], [100, 100, -2400]]

Output:
[None, -2200]

Pictorial Presentation:

Sample Solution:

Python Code:

#License: https://bit.ly/3oLErEI
def test(balances):
    firsts = []
    for bals in balances:
        total = 0
        for b in bals:
            total += b
            if total < 0:
                firsts.append(total)
                break
        else:
            firsts.append(None)
    return firsts 
balances = [[12, -7, 3, -89, 14, 88, -78], [-1, 2, 7]]
print("Bank deposits and withdrawals:")
print(balances)
print("\nFirst negative balance of deposits and withdrawals:")
print(test(balances))
balances = [[1200, 100, -900], [100, 100, -2400]]
print("Bank deposits and withdrawals:")
print(balances)
print("\nFirst negative balance of deposits and withdrawals:")
print(test(balances))

Sample Output:

Bank deposits and withdrawals:
[[12, -7, 3, -89, 14, 88, -78], [-1, 2, 7]]

First negative balance of deposits and withdrawals:
[-81, -1]
Bank deposits and withdrawals:
[[1200, 100, -900], [100, 100, -2400]]

First negative balance of deposits and withdrawals:
[None, -2200]

Flowchart:

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